As usual assume the rest of the board is settled and that tenuki or finishing in sente is not important.

(;AW[bd]AW[cd]AW[dd]AW[ad]AB[ae]AB[be]AB[ce]AB[de]AB[df]AB[ef]AB[ff]AB[fe]AB[ge]AW[fd]AW[gd]AW[ee]AW[ed]AB[he]AB[ie]AB[jf]AB[jg]AB[je]AB[ig]AB[hh]AB[ih]AB[eg]AB[eh]AB[fh]AB[gg]AW[gf]AW[hg]AW[gh]AW[gi]AW[hd]AW[id]AW[jd]AW[kd]AW[ke]AW[kf]AW[kg]AW[jh]AW[ji]AW[ii]AW[hi]AW[fi]AW[ej]AW[dj]AW[cj]AW[dg]AW[dh]AW[cg]AB[ch]AW[bi]AW[ei]AB[kh]AB[ki]AB[kj]AB[kk]AB[jj]AW[ik]AW[jk]AW[hk]AW[il]AW[lh]AW[li]AW[lj]AW[lk]AB[ll]AB[ml]AB[nl]AB[jl]AB[jm]AB[km]AB[im]AB[hm]AB[hl]AB[gl]AB[fl]AB[fk]AB[fj]AW[lg]AW[ij]TR[ij]MA[fg]C[Black took the ko and white answered with the triangle threat to capture 5 stones. What do you do ?]AP[goproblems]
(;B[hf];W[kl]C[Actually you don't have to sacrifice these stones. You can save them AND find life for the upper group.])
(;B[kl];W[fg]LB[hf:a]C[please play at (a) now]
(;B[hf];W[gg]
(;B[bg];W[ag]
(;B[cf];W[di]
(;B[ah];W[bh]
(;B[af]C[Nice, your group is alive with 2 eyes !RIGHT])
(;B[bf];W[ai]C[No potential for 2 eyes.]))
(;B[bh];W[ah]C[Eye is false, black is dead.])
(;B[af];W[ah]C[Eye is false, black is dead.])
(;B[bf];W[bh]C[No potential for 2 eyes.]))
(;B[ah];W[bh]
(;B[af];W[cf]C[False eye, your group is dead.])
(;B[bf];W[ai]C[White is not even forced to take at A11, the eye was false anyway.])
(;B[ai];W[aj]C[Please be serious.])
(;B[cf];W[bf]C[Black cannot even respond in A14 it would simply be atari.]))
(;B[bh];W[ah]
(;B[af];W[ai]
(;B[ci];W[di]
(;B[bf];W[cf]C[All group is in atari.])
(;B[bj];W[bf]C[Black is dead.]))
(;B[cf];W[di]C[Eye is false, black is dead.])
(;B[bf];W[ci]C[Black is dead.]))
(;B[cf];W[di]C[Eye is false, black is dead.])
(;B[bf];W[ci]C[No potential for 2 eyes.])
(;B[ci];W[di]C[Not fooling anyone, black is dead lost.]))
(;B[af];W[ah]
(;B[bh];W[ai]
(;B[ci];W[di]
(;B[bf];W[cf]C[All group is in atari.])
(;B[bj];W[bf]C[Black is dead.]))
(;B[cf];W[di]C[Eye is false, black is dead.])
(;B[bf];W[ci]C[Black is dead.]))
(;B[cf];W[di]C[Eye is false, black is dead.])
(;B[ci];W[bh]C[Black has nothing.])
(;B[di];W[ci]C[Black has nothing.]))
(;B[bf];W[bh]C[No potential for 2 yes.]))
(;B[bh];W[bg]C[There is no potential for 2 eyes.])
(;B[bf];W[bg]C[There is no potential for 2 eyes.])
(;B[cf];W[bg]C[There is no potential for 2 eyes.])
(;B[ag];W[bg]C[There is no potential for 2 eyes.])
(;B[af];W[bg]C[There is no potential for 2 eyes.]))
(;B[cf]C[NOTTHIS])
(;B[bf]C[NOTTHIS])
(;B[bg]C[NOTTHIS])
(;B[bh]C[NOTTHIS])
(;B[af]C[NOTTHIS])
(;B[ag]C[NOTTHIS])
(;B[ah]C[NOTTHIS])
(;B[ci]C[NOTTHIS])
(;B[di]C[NOTTHIS])
(;B[if]C[NOTTHIS])
(;B[ai]C[NOTTHIS]))
(;B[bg];W[kl]C[Well, this is the right idea, but wrong move order. If you saw you can make an eye here, there is no reason to sacrifice L10 stones, save them at once then play here.])
(;B[fg];W[kl]C[If you wanted to take the ko, just play H14 first move. Anyway you don't have to sacrifice L10 stones.]))